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Old 05-10-2013, 10:05 AM   #1
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Default GM 5.7 CPFI no power at fuel pump relay

This is in a 01 Workhorse, like the old P30 vans GM made. I could not get a workhorse wiring diagram, but found that a 01 Savanah with a 5.7 is the same. Wire colors and pin locations at ECM are correct to the diagram that im using. Iam not getting power to green and white wire which is the signal wire from fp relay to ECM. I have good ground at relay.I have power at orange wire at relay. I can jump the relay and power pump as well. All fuses are good. I checked grn/wht wire for good continuity between relay and pin 9 at ECM. No corrosion at relay or ECM connectors. No active codes. I've been through GM service manual and followed troubleshooter tree for Crank No Start it redirects me to Fuel Pressure troubleshooter. I do not get power for the key on 2 second prime, or when its cranking. I tried to command fp relay on/off with my scanner and it will not give me any power at the wire and when i go to run the relay test it says connection error and backs me up a screen. The trees next step was to replace ECM. But before I did that I wanted to check for good power and ground going into ECM which the book did not ask me to do. I had 2 good 12v wires going in. 1 good 12v switched power with key and good grounds. I not only measured voltage I also load tested it with head lamp on both powers and grounds. So i replaced the ECM, I ordered it direct from Workhorse they flashed new ECM to my VIN. I received new ECM and that did not fix anything. So i called Workhorse told them I wasn't getting power on the pin 9 for fp relay signal. They thought that I had received a bad ECM and overnighted me another one already programmed as well. Same problem still no power on pin 9. I have replaced a pick up module in the past and even if it wasn't working properly I believe I should still get my 2 second prime when i turn the key on since it only tells the ECM that the engines spinning over and it needs to pump fuel. If anyone has any ideas on what to look for next, I am open to suggestions. Thanks David
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